agent

a·gent

(ā'jent),

1. An active force or substance capable of producing an effect. For agents not listed here, see the specific name.

2. In disease, a factor such as a microorganism, chemical substance, or a form of radiation, the presence or absence of which (as in deficiency diseases) results in disease or in more advanced form of disease.

adrenergic neuron blocking agent one that inhibits the release of norepinephrine from postganglionic adrenergic nerve endings.

alkylating agent a cytotoxic agent, e.g., a nitrogen mustard, which is highly reactive and can donate an alkyl group to another compound. Alkylating agents inhibit cell division by reacting with DNA and are used as antineoplastic agents.

blocking agent an agent that inhibits a biological action, such as movement of an ion across the cell membrane, passage of a neural impulse, or interaction with a specific receptor.

calcium channel blocking agent any of a class of drugs that inhibit the influx of calcium ions across the cell membrane or inhibit the mobilization of calcium from intracellular stores; used in the treatment of angina, cardiac arrhythmias, and hypertension.

chelating agent

1. a compound that combines with metal ions to form stable ring structures.

2. a substance used to reduce the concentration of free metal ion in solution by complexing it.

cholinergic blocking agent one that blocks or inactivates acetylcholine.

Agent Orange a herbicide containing 2,4,5-T and 2,4-D and the contaminant dioxin; it is suspected of being carcinogenic and teratogenic.

oxidizing agent a substance capable of accepting electrons from another substance, thereby oxidizing the second substance and itself becoming reduced.

potassium channel blocking agent any of a class of antiarrhythmic agents that inhibit the movement of potassium ions through the potassium channels, thus prolonging repolarization of the cell membrane.

progestational agentprogestin: any of a group of hormones secreted by the corpus luteum and placenta and, in small amounts, by the adrenal cortex, including progesterone; they induce the formation of a secretory endometrium. Agents having progestational activity are also produced synthetically.

AgentChoice in dying An adult appointed by the declarant, under an advance directive executed or made in accordance with the legal provisions, to make health care decisions for the declarant. VA Bd of Medicine, 1997-98 § 54.1-2982Epidemiology A factor (such as a microorganism, chemical substance, or form of radiation) whose excessive presence, or relative absence (in deficiency states), is essential for the occurrence of a disease.Health insurance An insurance company representative licensed by the state who solicits, negotiates, or effects insurance contracts and who provides services to the policyholder for the insurer.Infomatics A small mobile piece of computer software that can send itself across a computer network and perform a task on a remote machine.Medspeak A thing capable of producing an effect.Military A code term for a biological substance that can be used as a weapon of mass destruction.Nutrition A substance added to a food to change a physical property.Pharmaceutical industry An authorised person who acts on behalf of or at the direction of a manufacturer, distributor, or dispenser, not including a common or contract carrier, public warehouseman, or employee of the carrier warehouseman. VA Bd of Pharmacy, 7/97.Pharmacology Any substance capable of producing a physical, chemical or biologic effect.Virology An unidentified virus or pathogen.

agent

Clinical pharmacology An authorized person who acts on behalf of or at the direction of a manufacturer, distributor, or dispenser, which does not include a common or contract carrier, public warehouseman, or employee of the carrier warehouseman Choice in dying An adult appointed by the declarant under an advance directive, executed or made in accordance with the legal provisions, to make health care decisions for the declarant. See Declarant Epidemiology A factor, such as a microorganism, chemical substance, or form of radiation, whose excessive presence, or in deficiency diseases, relative absence, is essential for the occurrence of a disease Medtalk A thing capable of producing an effect. See Biological agent, Challenge agent, Controlled drug substance Scheduled agent, Cytoprotective agent, Cytotoxic agent, Dirty agent, Gene transfer agent, Intercalating agent, Nerve agent, Radiopaque contrast agent, Reducing agent, Reversal agent, Schedule I agent, Schedule II agent, Thrombolytic, Vesicant/blistering agent Pharmacology Any substance capable of producing a physical, chemical or biologic effect. See Alkylating agent, Antidiabetic agent, Antimitotic agent, Antineoplastic agent, Antiplatelet agent, Antipsychotic agent, Chemotherapeutic agent, Depolarizing agent, Inotropic agent, Keratolytic agent, Negative inotropic agent, Nondepolarizing agent, Positive inotropic agent Virology An unidentified virus or pathogen. See Creutzfeldt agent, Hawaii agent, Norwalk agent, Pittsburgh pneumonia agent, TORCH agent, TWAR agent.

AGENT

Cardiology A clinical trial–Angiogenic Gene Therapy

a·gent

(ā'jĕnt)

1. An active force or substance capable of producing an effect.

2. A factor such as a microorganism, chemical substance, or a form of radiation, the presence or absence of which (as in deficiency diseases) results in disease or more advanced disease.

[L. ago, pres. p. agens (agent-), to perform]

a·gent

(ā'jĕnt)

1. An active force or substance capable of producing an effect.

2. In disease, a factor such as a microorganism, chemical substance, or a form of radiation, the presence or absence of which (as in deficiency diseases) results in disease or in more advanced form of disease.

[L. ago, pres. p. agens (agent-), to perform]

agent(s),

n1. a person or product that causes action. n2. a person authorized to act for, or in place of, another.

agent, adrenergic blocking,

n a drug that blocks the action of the neurohormones norepinephrine and/or epinephrine or of adrenergic drugs at sympathetic neuroeffectors.

agent, adrenolytic blocking

n an uncertain term sometimes used in reference to adrenergic blocking agents.

agent, anesthetic,

n a drug that produces local or general loss of sensation.

agent, antianxiety,

n any medication prescribed to relieve anxiety disorder symptoms, primarily stress and insomnia. The most common forms are benzodiazepine derivatives.

agent, antiarrhythmic

n.pl a substance used to prevent or relieve an irregular rhythm of heartbeat. Also mistakenly called antidysrhythmic.

agent, antigingivitis,

n compound that inhibits, controls, or kills organisms associated with the formation of gingivitis.

n a substance used to treat various nervous system and psychiatric disorders; possible effects on fetal development include sluggishness, oxygen deficiency, and physical malformations.

agent, antiparasitic,

n an antimicrobe that specifically targets pathogenic microorganisms.

agent, blocking,

n an agent that occupies or usurps the receptor site normally occupied by a drug or a biochemical intermediary (e.g., acetylcholine or epinephrine).

agent, bonding,

n a substance used to bond fillings and tooth restorations to the tooth surface.

agent, chemotherapeutic

n a chemical of natural or synthetic origin used for its specific action against disease, usually against infection.

agent, cholinergic blocking

n1. a drug that inhibits the action of acetylcholine or cholinergic drugs at the postganglionic cholinergic neuroeffectors. n2. an anticholinergic agent.

agent, cleaning,

n.pl an abrasive substance contained in toothpastes, gels, and powders that polishes teeth and aids in the removal of stains and plaque biofilm. See also abrasion, dentifrice.

agent, coloring,

n.pl any substance contained in toothpastes, gels, and powders purely to make the product more appealing.

agent, coupling,

n a substance or material that binds to both resin and reinforcement material and helps join them to make a composite.

agent, ganglionic blocking

n a drug that prevents passage of nerve impulses at the synapses between preganglionic and postganglionic neurons.

agent, myoneural blocking,

n a drug that prevents transmission of nerve impulses at the junction of the nerve and the muscle.

agent, oxidizing,

n an agent that provides oxygen in reaction with another substance or, in the broader and more definitive chemical sense, a chemical capable of accepting electrons and thereby decreasing the negative charge on an atom of the substance being oxidized.

agent, polishing,

n an abrasive that produces a smooth, lustrous finish.

agent, postganglionic sympathetic blocking,

n.pl a medication used to treat hypertension by blocking the release of the naturally occurring hormone norepinephrine.

agent, reducing,

n a category of chemicals used in film processing that brings out the gray tones of an image by creating black metallic silver from silver halide crystals.

agent, wetting,

n any agent that will reduce the surface tension of water. Generally used in investing wax patterns.

Whitening agent, before and after.

agent, whitening,

n a bleaching substance applied to teeth to lighten their appearance.

agents, antiadrenergic, centrally acting

n.pl antihypertensive drugs used to lower blood pressure, specifically those that operate by stimulating α-receptors in the central nervous system and arterioles.

agents, antianginal,

n one of several types of medication used to treat heart disease; alleviates pain associated with angina by lowering blood pressure during systole. See also vasodilator.

agents, oxygenating,

n.pl the substances, such as hydrogen peroxide, that, when used as mouthrinses, release oxygen into gingival tissues and reduce inflammation. The process has not proved to reduce the bacteria causing the inflammation. Long-term use may cause tissue damage.

agents, sympathetic,

n.pl the medications that stimulate the sympathetic nervous system by imitating the actions of naturally occurring norepinephrine and epinephrine. They may be used to treat cardiac arrest, nasal congestion, asthma, glaucoma, and attention deficit hyperactivity disorder and may cause anxiety, loss of appetite, and arrythmias. Also called adrenergic agents.

agent

1. any power, principle or substance by which something is accomplished, or which is capable of producing a chemical, physical or biological effect such as a disease.

2. of disease; any factor whose excessive presence or relative absence is essential for the occurrence of a disease.

adrenergic neuron blocking agent

one that inhibits the release of norepinephrine from postganglionic adrenergic nerve endings.

alkylating agent

a cytotoxic agent, e.g. a nitrogen mustard, which is highly reactive and can donate an alkyl group to another compound. Alkylating agents inhibit cell division by reacting with DNA and are used as antineoplastic agents.

anesthetic agent

substance capable of producing reversible general or local anesthesia.

anticholinergic agent

cholinergic blocking agent.

agent change

change in an animal's chemical or antigenic configuration can alter its pathogenicity. For example, a case of nitrate-nitrite poisoning in a cow can become a case of nitrite poisoning after conversion of the nitrate in the rumen. Mutation and antigenic drift are other types of change that vary agent pathogenicity.

chelating agent

a compound that combines with metals to form weakly dissociated complexes in which the metal is part of a ring, and is used to extract certain elements from a system.

chemical agent

substance that produces change by virtue of its chemical composition and its effects on living tissues and organisms.

cholinergic blocking agent

one that blocks the action of acetylcholine at nicotinic or muscarinic receptors of nerves or effector organs.

determinant agent

only some agents are determinants of diseases in that they always cause disease, and the same disease, and the disease does not occur without the agent. Many agents require the intervention of other factors, such as anaerobicity of tissue, hepatic insufficiency or physiological stress before they can establish their pathogenicity.

ganglionic blocking agent

one that blocks cholinergic transmission at autonomic ganglionic synapses.

an organism able to live in or on the tissue of a living animal; may not necessarily cause disease.

agent interaction

is the interaction between precipitating and predisposing causes of disease.

oxidizing agent

a substance that acts as an electron acceptor in a chemical oxidation-reduction reaction.

agent properties

are the properties which determine the pathogenicity of the agent, the solubility and acidity or biodegradability of a chemical, the virulence, adhesiveness, resistance to antibacterial agents of bacteria and viruses and so on.

reducing agent

a substance that acts as an electron donor in a chemical oxidation-reduction reaction.

surface-active agent

a substance that exerts a change on the surface properties of a liquid, especially one, such as a detergent, that reduces its surface tension. Called also surfactant.

therapeutic agent

a substance capable of producing a curative effect in a disease state.

agent without disease

exemplified by the orphan viruses. The agent is of a type that causes disease, but none is associated with the presence of the particular agent.

Patient discussion about agent

Q. Has anyone had an allergic reaction to gadolinium dye, MRI contrast agents, I have had a severe reaction. I would like to know the long term effects of this dye. And if anyone else has had or heard of problems and reactions to it. Please answer me. Thank you

A. In 1969 I almost died from the IVP dye. I had no idea I was allergic and when I awoke I was in a "recovery room." The doctor told me to always tell any physicians/paramedics etc of my allergy status regarding the dye. I now have chronic back pain, have a history of cancer in the family and the doctor wants to do a scan (including dye) but when I emphasized that I was allergic he backed off. Now I am wondering if there is anything else that can be done to test the bone (scan) without the dye. Any answers? Thanks

Q. Can anyone suggest a treatment for plantar fasciitis, apart from ultrasound, physio, anti-inflammatory agents? My friend has had Plantar Fasciitis for more than 1 year and has persevered with all the ususal treatments above plus lots of rest from weight-bearing and elevation.

A. Padded foot splints, silicone heels insert and special shoes (e.g. arch-supporting shoes) may also help. These are usually sold and fitted by a professional. Exercise is another important measure. Some patients benefit from avoiding walking barefoot or in sleepers but rather using shoes from the first step.

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